1. Technical Field
The present disclosure relates to a fuel cell system and a reformer for a fuel cell system. More particularly, the present invention relates to a fuel cell system and a reformer for a fuel cell system having an improved structure for supplying fuel and an oxidation gas.
2. Description of the Related Art
Fuel cells are an electricity generating system that generate electrical energy through a chemical reaction between hydrogen, which may be part of a hydrocarbon group fuel such as methanol, ethanol, and natural gas, and an oxidation gas supplied separately from the hydrogen.
Polymer electrolyte membrane fuel cell (PEMFC) typically exhibit superior output characteristics, lower operating temperatures, and fast starting and response characteristics, compared with other types of fuel cells. The PEMFC has been widely used as a portable power source for vehicles, a distributed power source for houses and public buildings, and a miniature power source for electronic devices.
A PEMFC system typically includes a stack, a reformer, a fuel tank, and a fuel pump. The stack forms a fuel cell main body that generates electrical energy by a reaction between hydrogen and oxygen, and the fuel pump supplies the fuel stored in the fuel tank to the reformer. The reformer generates hydrogen gas by reforming the fuel and supplies the hydrogen gas to the stack.
In the fuel cell system, since the reformer generates hydrogen gas from the fuel by a catalytic chemical reaction, the reformer includes a heat source for generating heat energy and a reforming reaction part for generating the hydrogen gas by a reforming reaction using the heat energy. The heat source generates the heat energy by an oxidation reaction between the fuel and the oxidation gas using an oxidation catalyst.
In a typical reformer, because the fuel and the oxygen are not uniformly distributed over the oxidation catalyst of the heat source, an oxidation reaction may occur locally, rather than over the entire heat source. Thus, temperature differences exist in the heat source by an incomplete oxidation reaction between the fuel and the oxygen. Accordingly, performance and heating efficiency of the entire reformer may be reduced by the temperature differences in the heat source.
In addition, in a typical reformer, backfire may occur at an end of a fuel injection nozzle, thereby causing additional temperature variation in the reformer.